In a known manner, eyeglasses comprise of a frame designed for holding the lenses to be worn by a user. The frame includes an optical face meant for accommodating the lenses, with or without the circle, and two side arms joined with hinges onto two end portions of the optical face between an open position (with the side arms deployed or extended in order for the eyeglasses to be worn) and a closed position (with the side arms folded against the optical face).
Conventionally, a side arm has at least one inner longitudinal surface that is not visible when the eyeglasses are worn, and at least one outer longitudinal surface that is visible when the eyeglasses are worn. The side arm may also have various different cross sectional shapes, such as flat, circular, triangular, rectangular, square, etc. Thus, a side arm with flat cross section has two inner and outer longitudinal surfaces that are substantially planar, a side arm with circular cross section has two inner and outer longitudinal surfaces that are curved, a side arm with triangular cross section has one inner longitudinal surface that is planar and two outer longitudinal surfaces that are flat and bevelled, a side arm with a rectangular or square cross section has one inner longitudinal surface that is planar and three planar longitudinal surfaces respectively on the lateral-, upper- and lower sides, etc. A side arm also has a tiny front end surface extending transversely to the two longitudinal surfaces over a front end of the arm, and more particularly extending substantially orthogonally to the main longitudinal direction of the side arm.
The articulated joint is generally in the form of a hinge comprising a fixed knuckle mounted on the end portion of the optical face, a movable knuckle attached to the front end of the side arm, in particular on its inner longitudinal surface, and a hinge pin (joint axis) linking the two knuckles in rotation and extending in a substantially parallel manner to the front end surface of the side arm and substantially orthogonally to the main longitudinal direction of the side arm.
When the side arm is opened, the front end surface of the side arm is facing a rear end surface of the relevant end portion of the optical face. This end portion may be present in the form of a tenon projecting towards the rear of the optical face or indeed of a portion of the optical face extending over the exterior alongside the lenses.
To decorate a frame for eye glasses, it is a known practice from the document U.S. Pat. No. 3,582,192 A to provide a decorative piece for the eyeglass side arm which is slidably mounted around the side arm, the side arm forming a rail over which has been slid the decorative piece with U shaped cross section. In order to hold this decorative piece in place, a compressible and magnetic strip is provided on the outer longitudinal surface of the side arm.
From the document US 2007/0242211 it is also a known practice to provide a notch forming a dovetail slide channel on the outer longitudinal surface of the side arm to receive a decorative piece which is slidably engaged in this slide channel.
From the document FR 2 886 024 A1 it is also a known practice to attach an ornamental element, embellishing trim on the eyeglass side arm, by means of a groove provided on the front end of the inner face of the side arm for receiving a hook of the embellishing trim, a hole provided on the outer longitudinal surface of the arm, on the side of its rear end, for receiving a droplet pin of the embellishing trim, and a retaining element disposed in a recess provided on the outer longitudinal surface of the side arm, between the front end and the hole, this retaining element being in particular a magnet, an adhesive strip, a snap-in locking mechanism, or a hook and loop strip fastening system.
These eyeglasses however present the disadvantage that, once the decorative piece is removed, the arm present is very unattractive, both with respect to the eye glasses in document U.S. Pat. No. 3,582,192 A where the compressible and magnetic strip remains in place, for the eye glasses in US 2007/0242211, where the notch remains visible, and for the eye glasses in FR 2 886 024 A1 where not only the groove, the hole and/or the retaining element remain visible once the embellishing trim has been removed, but also the misalignment of the outer surfaces of the side arm and the end portion of the optical face, such that it is not aesthetically recommended to do without the decorative pieces with such frames.
Furthermore, from the document U.S. Pat. No. 4,903,375 it is also a known practice to provide for the mounting of a spring clip on a side arm of the eye glasses in order for them to be supported over a garment pocket. The fastening of the spring clip on the side arm is obtained by means of spring rings which tighten one appendage of the clip against the arm; these rings being furthermore engaged in annular notches provided on the circumference of the arm. Over and above the difficulty of engaging the appendage of the clip in the rings, the annular notches and the rings on the side arm are particularly unsightly and unappealing, especially when the clip is not present.